Miniature display devices are useful in applications such as portable displays for video simulation applications, among others. A miniature display in the context of this discussion is understood to be a display sufficiently small that it requires an optical magnification arrangement to be effective. An advantage of such a display is that it consumes less power, and occupies much less space than a conventional display having real dimensions equal to the apparent dimensions of the magnified miniature display.
Such miniature displays can be sufficiently small that they can be incorporated in goggles or other eyewear. This may be used to "immerse" a user completely in a displayed environment, in what are popularly termed "virtual reality" interactions with a computer. Such a display may also be worn as an accessory display which allows a user to see his or her real environment in addition to information conveyed by the display. Such an accessory display may be useful, for example, as a display for a telephone operator or an airline ticket agent. Wearing such a display allows a user to maintain a comfortable fixed viewing relationship to the display while being free to move about to perform other activities.
U.S. Pat. No. 4,934,773 describes a miniature full-page video display which includes at least one row of light emitting elements such as light emitting diodes (LEDs), a magnifying lens, and a vibrating mirror in a light-tight box having an opening through which the vibrating mirror may be viewed. The LEDs are selectively illuminated at points in the travel of the vibrating mirror, resulting in rows of pixels or image-elements being projected at selected points on the mirror to provide a two-dimensional image. A head-mounted display system incorporating this miniature display concept is described in U.S. Pat. No. 5,003,300.
The row of such emitters may be formed on a single semiconductor chip, generally termed a microchip-laser array. Associated driving circuits for the emitters (one for each emitter) may be formed on the same chip. It is taught in the '773 patent, that by using two or more rows of light emitters, each row emitting a different colored light, a colored display may be achieved
A display device as described in the above-discussed patents offers the advantage that, by virtue of the scanning action of the vibrating mirror, a single row of light emitters can be made to do the work of as many such rows of emitters as would be necessary to provide a real two-dimensional display of the same resolution. This provides for a significant reduction in device complexity and cost. Usefulness of such a device is limited however, by a rate at which each light emitter can be modulated. Further, the physical size of LEDs and end-emitting semiconductor laser devices also limits the attainable resolution of such a device.
Notwithstanding the technical progress in miniature display devices to date, it is believed that further improvement of such devices, particularly in the direction of higher resolution and lower power-consumption is required.